Pressure-induced topological changes in Fermi surface of two-dimensional molecular conductor

T. Kobayashi; K. Yoshimi; H. Ma; S. Sekine; H. Taniguchi; N. Matsunaga; A. Kawamoto; Y. Uwatoko

doi:10.1103/physrevmaterials.9.l021801

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arXiv · 2501.08635

Pressure-induced topological changes in Fermi surface of two-dimensional molecular conductor

T. Kobayashi·K. Yoshimi·H. Ma·S. Sekine·H. Taniguchi·N. Matsunaga·A. Kawamoto·Y. Uwatoko

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Abstract

We demonstrated X-ray structural analysis of the pressure-induced superconductor, $\beta'$-ET$_2$ICl$_2$ under extremely high-pressure conditions, where ET denotes bis(ethylenedithio)tetrathiafulvalene. This material has been known as the highest transition temperature ($T_c$) superconductor among organic superconductors ($T_c=14.2$ K at $8.2$ GPa). On the basis of the experimental results, ab-initio models were derived using the constrained random phase approximation. We revealed that the Lifshitz transition exists behind the Mott insulator-metal transition and found that the value of the on-site Coulomb interaction was halved to around $10$ GPa compared to that at ambient pressure. This study clarifies the enigmatic origins of high $T_{\rm c}$, and concurrently, provides a new understanding of the impacts of structural alterations in organic materials under high pressure on their electronic properties and the superconductivity process.

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T. Kobayashi, K. Yoshimi, H. Ma, S. Sekine, H. Taniguchi, N. Matsunaga, A. Kawamoto, Y. Uwatoko. 2025-01-15. Pressure-induced topological changes in Fermi surface of two-dimensional molecular conductor. https://doi.org/10.1103/physrevmaterials.9.l021801

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